You can’t have a discussion about high-performance Audi models without referencing the one that started it all. Quattro, the Italian word for the number four, adorned the backside of its boxy coupé that made its debut at the Geneva motor show in 1980. It was a game-changer for the brand: while peers went the rear-wheel drive route, Audi wanted to give its customers four-wheel drive traction, the promise of confidence in every conceivable weather setting...